Evaluation of models for assessing compliance with environmental radiation regulations

The use of environmental transport and dosimetry models to predict the consequences of radionuclide releases from nuclear facilities is discussed. It is pointed out that many input parameters, and hence the predictions, of these models have a high degree of variability. The determination of the uncertainties of the predictions of these models is essential for assessing the adequacy of their use to ensure compliance with radiation protection standards. Estimation of the depletion of an airborne plume via dry deposition and the subsequent transfer of materials from air to ground were studied because values of deposition velocity as applied in assessment models are often misinterpretations of the values obtained from field studies. A sensitivity analysis revealed that at distances where most maximum individual exposures would likely occur as a result of routine releases from a nuclear installation, the plume depletion model commonly used is virtually insensitive to variations in deposition velocity. This is not true, however, for the estimation of deposition, which is a linear function of deposition velocity. Therefore, any variation in the value of the deposition velocity will bring about a like variation in the estimated deposition onto vegetation or ground. The uncertainty associated with the calculation of dose to an infant's thyroid as a consequence of the transport of elemental /sup 131/I via the grass-cow-milk pathway was studied as a function of air concentration. Probabilities were determined from a statistical analysis of reported values for deposition velocity, vegetation retention, and the grass-to-milk transfer coefficient

Computational Diagnostic Techniques for Electromagnetic Scattering: Analytical Imaging, Near Fields, and Surface Currents

This paper presents three techniques and the graphics implementations which can be used as diagnostic aides in the design and understanding of scattering structures: Imaging, near fields, and surface current displays. The imaging analysis is a new bistatic k space approach which has potential for much greater information than standard experimental approaches. The near field and current analysis are implementations of standard theory while the diagnostic graphics displays are implementations exploiting recent computer engineering work station graphics libraries

Compilation of documented computer codes applicable to environmental assessment of radioactivity releases. [Nuclear power plants]

The objective of this paper is to present a compilation of computer codes for the assessment of accidental or routine releases of radioactivity to the environment from nuclear power facilities. The capabilities of 83 computer codes in the areas of environmental transport and radiation dosimetry are summarized in tabular form. This preliminary analysis clearly indicates that the initial efforts in assessment methodology development have concentrated on atmospheric dispersion, external dosimetry, and internal dosimetry via inhalation. The incorporation of terrestrial and aquatic food chain pathways has been a more recent development and reflects the current requirements of environmental legislation and the needs of regulatory agencies. The characteristics of the conceptual models employed by these codes are reviewed. The appendixes include abstracts of the codes and indexes by author, key words, publication description, and title

Evaluation of selected predictive models and parameters for the environmental transport and dosimetry of radionuclides

Evaluations of selected predictive models and parameters used in the assessment of the environmental transport and dosimetry of radionuclides are summarized. Mator sections of this report include a validation of the Gaussian plume disperson model, comparison of the output of a model for the transport of /sup 131/I from vegetation to milk with field data, validation of a model for the fraction of aerosols intercepted by vegetation, an evaluation of dose conversion factors for /sup 232/Th, an evaluation of considering the effect of age dependency on population dose estimates, and a summary of validation results for hydrologic transport models